This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Canada's last epishelf lake drained into the Arctic Ocean following the 2020 breakup of the Milne Ice Shelf and will not recover, a new study confirms. Epishelf lakes form when an ice shelf acts as a dam, trapping a layer of freshwater floating above seawater connected to the ocean.
The Milne Fiord epishelf lake, located on northern Ellesmere Island in Nunavut, supported freshwater microorganisms near the surface and marine species below. In July 2020, the Milne Ice Shelf broke apart, losing 45% of its area and removing the barrier that held the freshwater in place. Drawing on a decade of ocean measurements, satellite imagery and field observations collected before and after the breakup, researchers from UBC, University of Alberta, Université Laval and Carleton University reconstructed the lake's disappearance.
Their findings show that the freshwater layer began escaping immediately after the collapse and had mostly vanished by autumn 2020. "The ice shelf and lake had been thinning for decades, but the 2020 breakup was the last straw. The lake drained within months," said study author Dr.
Jérémie Bonneau, a professor of civil and water engineering at Université Laval who conducted part of the research during his Ph.D. at UBC. The first field measurements collected after the breakup showed that by July 2022, brackish water had fully replaced the lake's distinct freshwater layer. Annual monitoring since then has found no sign of recovery.
"Epishelf lakes can signal when an ice shelf is under stress, and that's what we saw here," said co-author Dr. Bernard Laval, a professor of civil engineering at UBC who leads its environmental fluid mechanics research group. "The data showed the ice shelf was failing.
Once the ice is gone, the ecosystem goes with it. There's no coming back." "Epishelf lakes are remarkable because a freshwater ecosystem sits directly above a marine one, separated only by a thin boundary between fresh water and salt water," said co-author Dr. Andrew Hamilton, a research scientist at the University of Alberta who completed his Ph.D. research at Milne Fiord.
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